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Startups, Academics Focus on IoT's Weak Link: Power

December 01st, 2016
By Mary Catherine O'Connor
Batteries represent a design problem for Internet of Things devices, especially those used in very dense or widely distributed networks. But some researchers and startups believe they can address this shortcoming through energy harvesting.

Following a series of high-profile distributed denial of service (DDoS) attacks that leveraged thousands of poorly-protected Internet of Things devicesand following years of warnings from security experts that such an event was likelythe IoT industry is finally beginning to design better digital security features into products. But there is another elephant in the room, when it comes to the long-term viability and sustainability of IoT technology: the many shortcomings of battery-powered IoT devices.

Battery lifecycles vary widely, depending on the number of sensors supported, the amount of data collected and the frequency with which the battery-powered device collects and transmits data. In some use cases, a network of distributed IoT device could run for more than a decade before its battery needs to be replaced. In others, the batteries might last for only ten months or a year. In either case, the battery often represents an Achilles heel.

Lord Paul Drayson
But it does not have to be that way, says Lord Paul Drayson, a British entrepreneur and politician. During the 1990s, he ran a successful biotechnology firm, then served in a number of U.K. government positions before getting into electric vehicle racing and, in 2015, founding Drayson Technologies in order, in part, to tackle the IoT power problem.

"Individual sensors have energy requirements that add up, and if you look at IoT from the perspective of the whole system, it hits you that unless energy and data are addressed, IoT will not meet its potential," Drayson says. Aside from the material costs, disposal problems and labor implications that battery-operated IoT sensors present, he notes, there is also a supply problem, in that lithium is a limited resource.

Drayson Technologies has earned and has filed a number of patents used in Freevolt, an energy-harvesting technique that harvests ambient radio frequency (RF) energy from existing wireless and broadcast transmissions to trickle-charge sensors devices. (Drayson Technologies also develops machine-learning software to manage IoT networks to create smart sensor networks used in business applications.)

Drayson Technologies has commercialized Freevolt via CleanSpace, a project in which individuals (including a group of bike messengers in London) are issued sensors that track carbon monoxide and ambient temperature and transit this data to a carrier's cellular phone via a Bluetooth connection. The sensors contain a dedicated transmitter that basically sniffs for ambient RF energy. Once a sufficient RF density is available, it uses inductive power transfer to charge the device. The sensor data collected is used to crowdsource a real-time air-quality map of London, and, through partnerships with businesses, individuals who carry the CleanSpace device receive discounts if they pledge to drive less, thereby reducing their personal contribution to air pollution.

"Energy density from [ambient] RF is going up all time," Drayson states. "So functionality [of energy-harvesting devices] is going to increase." However, he explains, when energy-harvesting techniques are applied, energy efficiency must be designed into everything from the circuit design to the software, to how the devices are programmed. To control those variable, Drayson Technologies is deploying end-to-end solutions.



Freevolt is just one of many technologies being developed and applied around the world to generate energy from "free" and unlimited sources. Not all of these techniques are being applied to IoT systems, and not all approaches involve totally replacing the batteryfor example, new pacemakers are being developed that exploit vibrations from each heartbeat to continuously charge the device's battery. One of the most widely deployed energy-harvesting techniques, used in both IoT and non-IoT applications, is to exploit solar energy using photovoltaic panels. But vibrationsfrom sources ranging from engines to the footsteps of passerbyand friction are also being used to generate energy using piezoelectric transducers or a newer type of technology, called triboelectric nanogenerators.

At Finland's Tampere University of Technology, researchers are developing a new approach to IoT network design, in which the sensors would be widely distributed but would require neither batteries nor conventional silicon chips. Instead, the circuits would be printed and would harvest microwatts of energy from ambient sources (such as sunlight, RF or thermoelectricity) in order to transmit very small amounts of data to more sophisticated devices that would collect and analyze the sensor data, and then send usable data up to an IoT platform.

A Freevolt-powered tag
The project, known as the Printed, energy-Autonomous UniversaL (PAUL) platform for multifunctional wireless sensors and devices, is funded by Tekes, The Finnish Funding Agency for Innovation, and leverages advanced materials and diode designs. The devices will contain supercapacitors, which store energy in an electric field (whereas batteries use a chemical reaction to store energy). Supercapacitors survive hundreds of thousands more charge and discharge cycles than batteries, and thus have significantly higher lifecycles.

Paul Berger, a professor of electrical engineering and physics at Ohio State University, is helping to develop the technology as a visiting professor at Tampere University, and says that in addition to having long lifecycles, the PAUL devices will not depend on conventional silicon chips. This is important, he notes, because with the need to scale into the trillions, building sensors using silicon chips would not be economically or environmentally feasible.

"The production of silicon uses huge amounts of water," Berger explains, "and a silicon fab uses most of the elements in the periodic tableboth benign and toxic materials, in everything from etching to doping materials. Some of these are very toxic."

Plus, says professor Donald Lupo, Berger's collaborator and the head of the organic and nanoelectronics group at Tampere University's department of electronics and communications engineering, to manufacture "the trillions of chips needed [for the largest IoT forecasts], you'd need five or ten times as many [silicon] fabs in the world as you have now."

In the long run, the pair report, they hope to advance printed electronics to the point at which printed sensors could measure variables such as temperature or humidity every five seconds, and then (provided that the variables exceed a set threshold) forward the collected data to a central server.

Berger and Lupo say they are currently in discussions with a few organizations about the technology and hope to pilot the system in a couple of years. They then expect it to be made commercially viable around 2020.